The U.S. Supreme Court usually saves its biggest decisions for the last few days of a term, and this year is no different.

MONTAGNE: The court is expected to wrap up its current term today, but not before issuing major decisions on the legality of same-sex marriage. Yesterday, the court, in essence, cut the heart out of the landmark 1965 Voting Rights Act. That decision means nine states - mostly in the South - will be free from federal oversight when they change their election laws.

GREENE: By a slim one vote majority, the court declared that that the formula determining which states are subject to special federal scrutiny is invalid because it is based on old data.

NPR legal affairs correspondent Nina Totenberg has more.

NINA TOTENBERG, BYLINE: The Voting Rights Act, widely viewed as the most effective civil rights law in American history, features a unique provision. It requires nine states, most of them in the South, to clear any change in voting laws or rules in advance with the Justice Department or a federal court in Washington.

The provision was adopted to prevent jurisdictions with a history of racial discrimination from adopting new discriminatory provisions if old ones were struck down. To prevent the covered jurisdictions from of playing a kind of legal rope-a-dope with minorities, the designated areas had to pre-clear voting changes, and that meant that officials in Washington could and did prevent discriminatory changes from going into effect.

The hitch was that after 1975, Congress made no changes to the formula. And yesterday, Chief Justice John Roberts, writing for the five justice court majority, said that doomed the pre-clearance section of the law. The chief justice pointed to Selma, Alabama as an example of a place where a young John Lewis, now a congressman, was brutally beaten while marching for the right to vote in 1965.

Today, Roberts observed, Selma has an African-American mayor. Our country has changed, he said, and while any racial discrimination in voting is too much, Congress must ensure that the legislation it passes to remedy that problem speaks to current conditions.

The normally soft spoken Congressman Lewis, however, was outraged.

REPRESENTATIVE JOHN LEWIS: Today the Supreme Court struck a dagger in the heart of the Voting Rights Act. They're saying, in effect, that history cannot repeat itself, but I say come and walk in my shoes. Voting rights have been given in this country and they have been taken away.

TOTENBERG: Lewis went on to call for a massive outpouring later this summer - for the 50th anniversary of the march on Washington - as a way to demand that Congress rewrite the coverage formula.

That sentiment was echoed by Sherrilyn Ifill, president of the NAACP Legal Defense Fund.

SHERRILYN IFILL: This decision is a game changer and leaves virtually unprotected minority voters in communities all over this country. We will not soft soap it. This is a real threat, but we believe strongly that Congress can fix it.

TOTENBERG: Privately, though, few if any voting rights experts really believe that Congress, particularly this very polarized Congress, will be able to adopt the necessary fixes. Politically, it's a non-starter, said one voting rights authority. Not going to happen, said another.

Richard Hasen, of the University of California Irvine School of Law, was unsparing in his verdict on the future of the pre-clearance section of the law.

RICHARD HASEN: Well, I think the bottom line is that section five is effectively dead.

TOTENBERG: That assessment was born out yesterday by comments from various members of Congress. Whereas, the previous GOP chairman of the House Judiciary Committee pushed through the 2006 Voting Rights extension and eagerly defended it as necessary, the current GOP chairman, Bob Goodlatte did quite the opposite yesterday.

REPRESENTATIVE BOB GOODLATTE: Quite frankly, I think there's an element of fairness in the court saying that you can't treat some jurisdictions differently than others.

TOTENBERG: And that, in fact, is why the coverage formula was never updated, because no jurisdiction wants to be labeled a new bad actor under a new formula. So it now appears that no jurisdiction will have to get advance approval for any voting change. And most, if not all, court battles over these laws will take place after the laws have gone into effect.

Voting rights authority Heather Gerken of Yale Law School.

HEATHER GERKEN: I don't see how anyone has enough resources to litigate those cases, given how much litigation costs and what are the stakes for each one of those issues individually.

TOTENBERG: NYU Law School's Richard Pildes thinks these fears are exaggerated, but he adds...

RICHARD PILDES: People died for the enactment of the statute. It is laden with as much historic significance and symbolism as any act of Congress in American history.